A structured light is a lighting with a specified pattern. With current optical technologies and their developments, the structured lighting can be designed to have a linear line, a planar with dot, stripe, or cross patterns, a grid pattern or even a more complicated light pattern. Consequently, the structured light can be applied to many fields, such as three-dimensional (3D) contour regeneration, distance measurement, anti-counterfeiting recognition, and so on. In other words, the applications of the structured light is emergently increased and the associated technologies have been widely researched and developed.
Please refer to FIGS. 1, 2A and 2B. FIG. 1 schematically illustrates a structured light projected to an object. FIG. 2A schematically illustrates the structured light pattern on the surface of the object, in which the distance between a structured light generation unit and the object is shorter. FIG. 2B schematically illustrates the structured light pattern on the surface of the object, in which the distance between the structured light generation unit and the object is longer.
As shown in FIGS. 1, 2A and 2B, a structured light generation unit 1 is used for projecting a structured light 2 to an object. When the light beams 21 of the structured light 2 are projected on the object, a structured light pattern 20 is formed on a surface 31 of the object. Moreover, the structured light 2 outputted from the structured light generation unit 1 has a beam diffusion angle θ, as to specified the extension range, in a kind of field angle, formed by the structured lighting. As the traveling distance of the light beams 21 of the structured light 2 increases, the coverage region of the structured light 2 is widened. That is, if the distance between the object and the structured light generation unit 1 is shorter, the structured light pattern 20a on the surface 31 of the object is smaller (see FIG. 2A). Whereas, if the distance between the object and the structured light generation unit 1 is longer, the structured light pattern 20b on the surface 31 of the object is larger (see FIG. 2B).
As mentioned above, the size of the structured light pattern 20 increases with the increasing distance between the object and the structured light generation unit 1. However, as the size of the structured light pattern 20 increases, the resolution of the structured light pattern 20 on the surface 31 of the object reduces. In case that the size of the structured light pattern 20b on the surface 31 of the object increases to a certain extent, the resolution thereof is too small to be utilized.
Therefore, there is a need of providing a scheme to increase the resolution of the structured light pattern in order to overcome the above drawbacks.